Description

The Northern Sandhill Frog is a smallish frog with body mass between 2 to 8 grams. Mature males achieve a snout-vent length of 26 to 30 millimeters, with adult females reaching 28 to 33 millimeters. Arenophryne rotunda has a distinct form based upon its forward burrowing habit. This frog has a diagnostic broad head and rotund body form, featuring a protective pad at its nose tip characteristic of forward burrowers. The front legs are powerful, built for forward digging. The legs are short, as well as the fingers and toes. Its broadly sculpted fingers are arrayed on spade-like hands, adapted for its forward burrowing habit (Tyler 1998).

Skin coloration may vary from off-white to cream to light green, overlain with irregular blotches of brown or brick-red speckles (Government of Western Australia 2010).

Phylogeny A closely related species, the Southern Sandhill frog, Arenophryne xiphorhyncha, was earlier thought to be identical to A. rotunda; however, more detailed analysis reveals this closely related species residing in the Kalbarri dunes, is a distinct taxon. These two taxa apparently genetically diverged approximately five to seven million years before present.

Species Associates There are a number of faunal associates in this coastal zone of the Southwest Australian savanna (Hogan and World Wildlife Fund 2012). Notable avifauna include the Near Threatened blue-billed duck (Oxyura australis), the Vulnerable fairy tern (Sterna nereis), and the Vulnerable fat eastern curlew (Numenius madagascariensis).

Notable reptile associates include a swimming skink, the Vulnerable Shark Bay ctenotus (Ctenotus zastictus), which is also found on the dunes of Shark Bay; and the Christina's lerista (Lerista christinae), a species also endemic to the coastal zone of the Southwestern Australian savanna; and the Endangered woma (Aspidites ramsayi).

Notable mammals with overlap or near overlap of range include the Near Threatened black-footed rock wallaby (Petrogale lateralis), although the limits of this wallaby's distribution have shrunk due to its recent population decline.

Barker, J., Grigg, G. C., and Tyler, M. J. (1995). A Field Guide to Australian Frogs. Surrey Beatty and Sons, New South Wales.

Roberts, J.D. (1984). ''Terrestrial egg and deposition and direct development in Arenophryne rotunda, a myobatrachid frog from the coastal sand dunes at Shark Bay, Western Australia.'' Australian Wildlife Research, 11, 191-200.

Tyler, M. J. (1998). Australian Frogs: A Natural History. Cornell University Press, Ithaca, New York.

Tyler, M.J., Smith, L.A., and Johnstone, R.E. (1994). Frogs of Western Australia. Western Australian Museum, Perth.